This invention relates to an improvement of a water-proofing plug for a connector used for connection of electric wires.
A water-proofing plug as shown in FIGS. 6 and 7 has been proposed by the present Applicant before (cf. Japanese Patent Application No. 121276/1989 laid open to the public on Aug. 17, 1989).
As shown in FIGS. 6 and 7, the waterproofing plug S comprises a rubber plug 1, and a reinforcing member 2 which is rigid. The rubber plug 1 is designed as follows: A sealing portion 1c is formed on the outer surface of one end portion of a cylinder 1a which has an electric wire inserting hole 1b along the central axis. The sealing portion 1c is elliptic in section so that it is brought into close contact with the inner surface of a connector housing. The other end portion of the cylinder 1a is formed into a connecting portion 1d, which is coupled to an electrical connecting piece. On the other hand, the reinforcing member 2 is designed as follows: Supporting arms 2c extend from both sides of an elliptic base plate 2a which has an electric wire inserting hole 2b at the center. The reinforcing member 2 is used in combination with the rubber plug 1 in such a manner that the supporting arms 2c of the former 2 are fitted in the sealing portion 1c.
The water-proofing plug S thus constructed suffers from the following difficulties:
The central axis of an electric wire 5 connected to the electrical connecting piece which is incorporated in the connector housing 3 with a rear holder 3a, is shifted to some extent from the central axis of the electrical connecting piece 4. Hence, when a force is applied to pull the electric wire along the central axis of the electric wire 5, the electrical connecting piece is raised, so that the end portions of a pair of stabilizers which extend from the tightening portion of the electrical connecting piece are brought into contact with the end faces 2d of the supporting arms 2c of the reinforcing member 2. In this case, the end faces 2d are substantially perpendicular to the central axis of the electric wire 5, and therefore the end portions of the stabilizers are brought into contact with the inner portions of the end faces. When the electric wire is further pulled, then the electrical connecting piece is further raised, so that the stabilizers 4b are spaced apart from each other, while the tightening portion 4a of the terminal goes into the space between the electric wire and the lower supporting leg 2c, which will greatly lower the terminal holding force, and the water-proofing characteristic of the water-proofing plug.